1. Field of the Invention
The present invention relates to regulators for underwater breathing apparatus and more particularly to the diaphragm and exhaust valve of second stage regulators.
2. Description of the Prior Art
In a typical underwater breathing apparatus, air or other breathable gas is supplied to a diver from a high pressure tank via a two stage regulating system. The regulator first stage is mounted to the high pressure tank valve and functions to reduce tank gas pressure to about 150 psi above ambient pressure. The tank and regulator first stage are carried by the diver on his back. A flexible hose conduit supplies the reduced pressure gas to a regulator second stage held by the diver's mouth with a mouthpiece. The second stage is a demand regulating device which opens to supply breathing gas at ambient pressure in response to inhalation effort. Provision is also made to exhaust exhaled gas through the mouthpiece into the water.
Inhalation suction pressure is sensed by a diaphragm within the second stage that cooperates with a lever to open a valve which controls the flow of gas to the diver. Whenever the diver stops breathing, or exhales, the diaphragm responds to the lack of inhalation suction by stopping the flow of gas. A separate exhaust valve is provided to permit the escape of exhaled gases. The exhaust valve, due to physical and dimensional constraints, is a component which is separate from the diaphragm and is typically located several inches away from the diaphragm.
The separation of the diaphragm and exhaust valve in the prior art is a shortcoming because whenever the swimming diver is oriented so that the exhaust valve is over (closer to the water surface than) the diaphragm, the exhaust valve is at a slightly lower pressure in the water than the diaphragm, and a sensitive diaphragm will respond to the slight loss of pressure through the exhaust valve by inadvertently turning "on" the regulator which results in an unwanted loss of breathing gas. The larger the separating distance between exhaust valve and diaphragm, the greater the waste of breathing gas. An object of the present invention is to close the spacing between the exhaust valve and diaphragm and thereby prevent the unnecessary waste of breathing gas.
Some configurations of prior art place the exhaust valve at the center of the diaphragm or actually combine the functions of diaphragm and exhaust valve. Such a configuration is disclosed in the inventor's U.S. Pat. No. 4,297,998 issued Nov. 3, 1981 entitled PILOT CONTROLLED REGULATOR SECOND STAGE. In this type of configuration, typically the flow of exhaled gases past the exhaust valve generates numerous bubbles as water is displaced by the expanding gas. These bubbles set up a lingering turbulence which can remain even after exhalation is completed and a new inhalation cycle has been initiated. Such turbulence disrupts the smooth operation of the mutually located, exposed diaphragm. Another object of the present invention is to isolate the closely spaced diaphragm and exhaust valve from each other such that exhaust bubbles do not interfere with the smooth operation of the diaphragm.
Another shortcoming of prior art is that the flow of exhaled gases is restricted by the limited size of the exhaust valve and related passages. Another object of the present invention is to provide an exhaust valve with flow passages which do not restrict the flow of exhaled gases.
Another shortcoming of prior art is that the diaphragm and exhaust valve are separate components which must be individually fabricated and mounted. An object of the present invention is to provide a diaphragm and exhaust valve which are a single component.